Circuit interrupter



June 9, 1942' R. T. KINTZING ET AL 2,285,986

CIRCUIT INTERRUPTER Filed Jan. 24, 1940 2 Sheets-Sheet l I 68 /0 1y 5F/yf.

- m 4 42 74 44 :2 48 64 WITNESSES: 44 60 42 3 and (/arence 5. Ear).

BY I! 36 Q 2/ ATTORNE Jim 9, 1942.

R. T. KINTZING ETAL CIRCUIT INTERRUPTER Filed Jan. 24, 1940 Fig. 6

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J/ZA Gibb/a1 2 Sheets-Sheet 2 IN VENTOR 5 Oswald D. van Nehren, fiee se7.' lf/n {Z07 and C/ar'e/vce 45 Gary 7Z8] ATT:O EY

Patented June 9,1942

UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Application January 24,1940, Serial No. 315,368

13 Claims.

Our invention relates generally to electric circuit interruptingdevices, and more particularly to switches 01' the push button type.

An object of our invention is to provide a novel, compact and simplifiedush button switch construction.

Another object of our invention is to provide a novel switch block orsupport construction.

Another object of our invention is to provide a novel and simplifiedarrangement for supporting switch contacts on an insulating supportingbase.

Another object of our invention is to provide a novel arrangement forsupporting conductor terminals on an insulating supporting block.

A further object of our invention is to provide novel supporting meansfor a plural push button switch unit.

A further object of our invention is to provide a novel locking meansfor selectively maintaining a button of a push button switch in oneoperating position.

Another object of our invention is to provide novel switch constructionsof different types, parts of which are interchangeable.

Another object of our invention is to provide a push button switchconstruction which is adapted to be mounted in difierent angularpositions.

A still further object of our invention is to provide novel push buttonswitch constructions which are rugged and eflicient and yet ofrelatively simple design, and capable of being economically constructed.

These and other objects of our invention will become more apparent uponconsideration of the following detailed specification of preferredembodiments thereof, taken in connection with the attached drawings, inwhich:

Figure 1 is a cross sectional view of a switch easing illustrating apush button switch in elevation therein constructed in accordance withone embodiment of our invention;

Fig. 2 is a plan view of the casing shown in Fig. l and looking at theright-hand side of Fig. 1;

Fig. 3 is an end view of the push button unit per se shown in Figs. 1and 2;

Fig. 4 is a cross sectional view taken substantially on the line IV-IVof Fig. 5;

Fig. 5 is a top plan view of the push button unit shown in Figs. 1 to 4with one push button, together with its associated spring and movingcontact, removed;

Fig. 6 is a top view of a single button push button switch unitconstructed in acordance with our invention;

Fig. 7 is a side view of the switch shown in Fig. 6

Fig. 8 is a bottom view of the switch shown in Figs. 6 and 7; and

' mounted in a box or casing. As shown in Figs. 1

and 2 there is provided a metallic casing 2 having one side open andprovided with knock-out portions 3 in opposite end walls thereof. Ournovel two button push button switch unit 4 comprises generally, aninsulating block 5 which may be of any desired insulating material,preferably of some molded insulating material. The block 5 is providedwith a pair of spaced integral projections 5 adapted to be received incorresponding depressions provided in the bottom wall of the casing 2,and the block is secured to this wall of the casing by a single machinescrew 8 extending through a substantially central bore ill in theinsulating block 5. A cover 12 is provided for the open side of thecasing 2, and is secured thereto as by the machine screws I3. The coverI2 is also of insulating material and may be of a molded insulatingmaterial if desided. The cover is provided with a pair of spacedapertures for receiving the push buttons H and ii for controlling thepush button unit 4. The cover is also provided with an oval integralridge l8 surrounding the push button openings, and with a lateral groove22 in which is secured a stationary lock bar 20. The bar 20 is securedin the groove 22 by means of a shouldered rivet 24 extendingtherethrough and through the cover l2. The rivet 24 has an enlargedbearing portion 26 adjacent the outer end thereof on which is movablymounted a latch bar 28. The latch bar 28 is provided with an elongatedslot 30 in which is received the bearing portion 26 of the rivet 24directly beneath the head of the rivet. Both the stationary lock bar 20and the movable lock bar 28 are provided with end apertures 32 and 34,respectively, for a purpose to be hereinafter described.

The purpose of the lock bar 28 is to be able to selectively retain thepush button l6 in a depressed position when desirable to preventaccidental energization of the circuit or to prevent unauthorizedpersons from tampering with the switch. Since the movable locking bar 28is freely rotatable and slidably mounted on the rivet 24, it is obviousthat when the push button I6 is depressed, the bar 28 may be moved fromthe position shown in full lines in Fig. 2 about the rivet 24, as apivot, into alignment with the stationary lock bar 20 and groove 22provided through the barrier i8, whereupon the bar 28 may be movedlongitudinally to a position in which it overlies the push-button l6,and where its aperture 32 coincides with the aperture 34 on thestationary lock bar 20. If desired, the movable lock bar 28 may belocked in this position, which is shown in dotted lines in Fig. 2, byengaging a conventional padlock or other locking means through thealigned apertures 32 and 34 of the two locking bars. When it is desiredto unlock the push button 16, a reverse procedure is followed; that is,the movable bar 28 is withdrawn longitudinally from the dotted lineposition shown in Fig. 2 where it overlies and maintains the push buttonIS in a depressed position, until the inner end thereof clears the sidesof the groove 22 so that it may fall to the depending position, shown infull lines in Fig. 2, assuming the switch is mounted vertically, asshown.

The insulating block of the push button unit 4 is provided at one endthereof with a pair of spaced outwardly projecting ledges 36, and at theother end thereof with a pair of similar ledges 38 slightly'spaced fromthe plane of the ledges 35. The ledges 36 and 38 are integral with theblock 5, and if the block is constructed of a molded insulatingmaterial, the ledges may be molded therewith. The ledges 35 ar adaptedto support substantially U-shaped contact strips 40 of any suitableconducting material, such, for example, as copper or the like.Similarly, the ledges 38 are each adapted to support a substantiallyU-shaped contact strip 42 similar to the strips 40. These contact strips40 and 42 may be preformed of a material having some degree ofresilience so that they may be slipped onto their respective ledges andfrictionally maintained thereon, or the contact strips may be bent abouttheir respective ledges into intimate engagement therewith so as to befrictionally maintained in place on the ledges. As shown, the contactstrips are bent about three sides of each ledge with the frictionbetween the strips and the ledges being relied upon to preventlongitudinal withdrawal of thei contact strips, and each ledge isprovided with an integral up-standing projection 43 at the outer side ofits respective'contact strip to pretends through the contact strips andinto an enlarged depression 46 in the insulating base 5. It should benoted that when the terminal screws are drawn down tightly so as toenter the depressions 46 in the insulating block 5 they form a positivelock for preventing end-wise with-- drawal of the contact strips fromtheir respective ledges. Each end of the insulating block 5' is providedwith an integral outwardly extending cylindrical barrel 48 fortelescopically receiving the push buttons I4 and I6, respectively. Thepush button I6 is provided with a stem 50, extending through theaperture in its associated barrel 48 and having a reduced lower end 58,forming a shoulder against which is seated a bridging contact 54, whichis held in place by means of a hairpin key 56 seated in a peripheralgroove in the reduced end of the stem 50. The push button I4 is providedwith a similar stem 50 on which is mounted a bridging contact 52 similarto the bridging contact 54. Coil compression springs (not shown) areprovided within the push button supporting barrels 48 to normally urgethe push buttons l4 and to an outwardly extended position. This normalposition of the switch is that illustrated in the drawings, Figs. 1 to5. The push button l4 has the bridging contact 52 positioned thereon soas to be normally outwardly of and out of engagement with the contactstrips 40. The bridging contact 54, controlled by the push button I6, isnormally positioned inwardly of and in engagement with the contactstrips 42, being held in this position by the aforementioned coilcompression spring. It can thus be seen that the upper end of the lowerleg of the U-shaped contact strips 40, as shown in Fig. 1, form contactsadapted to be bridged by the bridging contact 52 under control of thepush button l4. Similarly, the lower or short leg of the U-shapedcontact strips 42 provide relatively fixed contacts adapted to bebridged by the bridging contact 54 carried and controlled by the pushbutton It.

As stated above, the push buttons l4 and I5 are slidably mounted on thesupporting barrels 48, and the push buttons, as shown in Figs. 2 and 5,are preferably provided with suitable indicia to distinguish thebuttons, In order to provide for mounting this push button unit ineither a vertical or a horizontal position and still maintain theindicia on the push buttons in a position in which they are legible, wehave provided each push button with an integral key or projection 64 onthe inner wall thereof adapted to fit in keyways or grooves 60 and 52provided on the supporting barrels 48.

As shown in Fig. 5, the keyways 60 and 62 are positioned substantiallyapart so that the buttons may be assembled thereon in two positions'substantially 90 apart.

As shown in Figs. 3, 4 and 5, we have provided a strap 65 of conductingmaterial secured by ter-, minal screws 44 to connect contact strips 40and 42 so that this unit may be employed in a single control circuit ifdesired.

We have also provided integral guideways and insulating projections onthe insulating block 5, for positioning conductors to be attached to thecontact strips so that they will not interfere with the moving contactsand will be properly directed to the ends of the box and to the terminalscrews. As shown particularly in Fig. 5, such guide means compriseconcave guideways 68 provided laterally of each terminal screw 44, andintegral outwardly extending barriers "I0 terminating short of the baseof the insulating block 5 to form conductor passageways 12 between theends of the barriers 10 and the bottom wall of the housing 2. Thusconductors, in entering the housing 2, for example, through the lowerknock-out opening 3, as viewed in Fig. 1, are passed along the bottomwall of the casing through the passage 12, concave guideways 68 to oneof the lower terminal screws.

In order to prevent the conductors from escaping from under the heads ofterminal screws 44, when these screws are tightened, and to eliminatethe use of turned-up corners of the contact strips for this purpose, weprovide ledges I4 integral with the insulating block 5 and positionedclosely adjacent to the contact screws for a substantial portion of theperiphery of the heads of the screws. The ledges l4 lie suflicientlyclose to the terminal screws 44 so as to prevent a conductor fromescaping from beneath the head of the terminal screws when the screwsare tightened. As appears from Figs. 1 and 5, each terminal screw islocated in a partial pocket formed in the insulating block 5 and theblock is provided with integral barriers ll between the contact screwsthus providing a substantial creepage distance between all of theconducting parts.

When the switch unit is mounted in a casing such, for example, as thecasing 2, it may be diflicult to relate the several terminal screws totheir respective contacts upon inspection. Therefore, as shown in Fig.5, shoulders at each corner of the insulating block may be inscribedwith suitable indicia, such as the letters V, W, X, Y, shown in thisfigure to enable positive identification at a glance, as to the relationbetween each terminal screw and its respective contact strips. 7

In the embodiment shown in Figs. 6 to 9, we have illustrated a singlebutton push button switch unit for controlling two circuits. This isaccomplished by providing two sets of contacts spaced from each otherwhich are adapted to be bridged by a single bridging contact. Thisswitch unit comprises an insulating block I6 provided with ledges 90 andI8 around which are bent the contact strips 94 and 92, respectively, inthe same manner as the contact strips were mounted in the previouslydescribed embodiment of our invention. As shown in Fig. 7, each contactstrip is provided in its upper leg with a threaded aperture forreceiving the terminal screws 96 and the lower legs of the contactstrips are shown as extending into overlapping spaced relation to formthe spaced contacts referred to above. Movement of the contact stripsHand 84 relative to ledges I8 and 80 is prevented in this switchconstruction, by laterally extending wings or sides 90 which extendoutwardly from the insulating block I6 into engagement with the bightportions of the contact strips 82 and 84. Lateral movement of contactstrips 92 and 84, with respect to the insulating block I6 is preventedby integral projections 9I on the .ledges 19 and 90, provided in thisinstance on the lower sides of the ledges. Also, in this embodiment ofour invention, we have provided ledges 98 similar to the ledges I4 inthe previously described embodiment, adjacent the terminal screws 86 topres vent the escape of conductors from beneath the heads of thesescrews when the screws are tightened. Likewise, the terminal screws arelocated in partial pockets in the insulating block with barriers 93between them to increase the creepage distance between the conductingparts of the switch. The wings 90 extend the full heighth of the switchand include lower end portions comprising integral barrel portions 92,internally bored, as at 94, for the reception of bolts or other securingmeans for mounting this switch unit.

Referring to Fig. 9, it can be seen that the insulating block I6 isprovided with a central bore 96 having a reduced inner portion 99presenting a shoulder I00. It can be seen that the construction thus fardescribed is substantially the same, except in certain minor details, asthat shown in the copending application, Serial No. 230,937, of ClarenceE. Gary, for an improvement in Switches, and which application isassigned to the same assignee as this application. Thus, in thestructure thus far described, a rotatable actuating member carrying amovable bridging contact engageable with the inner edges of the contactstrips 92 and 94 may be inserted in the bore 96 in the manner taught inthe above-mentioned copending application, or the same structure may beprovided with a slidably mounted bridging contact to be actuated by apush button, as is shown in Figs. 6 to 9 of this application. Theunderside of block I6 is provided at one side of bore 96 with anintegral arcuate guide flange 91 (Fig. 8) for cooperation with arotatable bridging contact of the type disclosed in the above-mentionedcopending application.

If it is desired to use the insulating base 46 heretofore described inconnection with a push button, a push button I02 may be provided whichhas an integral skirt I04 telescoping over the outer surface of thesleeve portion I09 on the insulating block 16, and a stem I03 passingthrough the bore 96, 99 through the insulating block. The push buttonmay be provided with a key I05 in the same manner as the push buttons I4and I6 described in connection with the previous embodiment of ourinvention, which key or projection I05 is adapted to be received ineither of two keyways I01, provided on the sleeve I09. The keyways I01are substantially apart to thereby enable this particular switch unit tobe mounted in at least two diflerent angular positions.

The lower end of the push button stem I09,

as seen in Figs. 7 and 9, is provided with a reduced portion I06, havingan outer annular groove for receiving the hairpin key I00. The key I09is merely a substantially U-shaped strip of material of a size to fit inthe peripheral groove in the outer end of the stem I03, which, afterassembly, has the free ends thereof bent inwardly by any suitable meansto secure the same in position on the stem. The hairpin key I09 supportsthe bridging contact I I0 mounted on the reduced portion I06 of the stemI03, and the bridging contact is maintained in position against the keyI08by a coil compression spring H2 seated at its lower end on thebridging contact H0 and bearing at its upper end against the shoulderII4 formed between the stem I03 and the reduced portion I06 thereof. Asshown, the lower end of bore 96 is enlarged at 99 for receiving springII2. This enlarged end 99 of bore 96 is also adapted to receive thepositioning spring employed in the rotary switch of the aforementionedcopending application, and to this end is provided with opposed notchportions II to receive portions of the positioning spring to preventrotation thereof. A coil compression spring II 6 is provided within thesleeve I09 and is seated at one end on the shoulder I00 in the sleeveand at its other end bears against push button I02 to normally urge thesame upwardly so that the bridging contact normally connects the lowercontact portions of the contact strips 84. In order to prevent rotationof bridging contact I I0 on portion I06 of stem I 03, block I0 ispreferably provided with integral projecting guide members at theunderside of the block, and at the side of bore 96 opposite guide flange91. It will be noted that guide members 95 are also positioned to engageone edge of bridging contact IIO on opposite sides of stem portion I06,to thereby guide the bridging contact for rectilinear movement.

When the push button I02 is depressed, the bridging contact is moveddownwardly to bridge the lower legs of the contact strips 92, and thecoil compression spring II2 acts to provide resilient engagement of thebridging contact II0 with the lower legs of the contact strips 92, andalso provides some lost motion between the lower limit of travel of thepush button and the lower limit of travel of the bridging contact I I0.

Inasmuch as it is impossible to view the contact portions of the contactstrips 92 and 94 from the top or front of the switch when it is mountedon a support, as apparent from Fig. 6, it is desirable to providesuitable indicia adjacent the respective terminal screws 86 to indicateto a service man the association between the various contacts and eachrespective terminal screw. As shown in Fig. 6, the insulating block 16may be marked adjacent the two terminal screws 86 which are on thecontact strips 82 with the letter B to indicate their association withthe bottom switch contacts, and the block may be marked adjacent theother terminal screws with the letter T to indicate the top switchcontacts. Instead of such marking, or in addition, the contact screwsthemselves, at opposite ends of the switch unit may be of differentmaterial or of material which is of different color. Thus, the contactscrews at one end of the switch may be of brass, whereas the contactscrews might have a coating of tin thereon.

The switch unit of this embodiment of our invention is also providedwith guide passages for receiving conductors to be connected to theterminal screws 86. As shown, for example, in Figs. 6, 7 and 8, groovesH8 are provided between the side wings 90 and the ledges I8 and 80 ofthe contact strips 82. Conductors secured to the terminal screws mayeach be led downwardly as viewed in Fig. 7, through the adjacent grooveH8 and thence through arcuate cut-out portion I20 at the correspondingcorner of the insulating block I26.

From the foregoing it should be apparent that we have provided at leasttwo novel types of push button switch units, and a casing for a pushbutton switch unit embodying an insulating cover, thus making itpossible to permit a smaller space between the current carrying parts ofthe switch and the cover, and thus reducing the depth of the casing. Inboth embodiments of our invention we have located the terminal screws insuch a manner adjacent insulating ledges, that after a connecting wirehas been slipped over the screws and secured beneath the head of eachscrew, it cannot slip outof place. Also, in both embodiments of ourinvention, conducting strips are frictionally secured to an insulatingswitch block, and are additionally prevented from separation from theblock in some instances by projections integral with the block, and inanother instance by the contact strip terminal screw. Hairpin keys areprovided to lock the movable contact in place, and our two button pushbutton switch unit may be mounted with but the use of a single screw.Both forms of our invention are provided with insulating blocks havingintegral barriers and guideways to receive and position the conductorsleading to the switch, and especially to maintain such conductors awayfrom the moving contacts. Both forms of push button units disclosed maybe mounted in either oftwo positions substantially 90 apart with thelegend on the buttons being readable in either position. We have alsodisclosed a latch or lock element which is operable to maintain a pushbutton depressed and which may be itself locked in such a position.Also, we have disclosed in Figs. 6 to 9, an insulating block unitprovided with contacts so arranged that they may be used with either arotary movable contact, or a slidable push button type of movablecontact.

Having described preferred embodiments of our invention, in accordancewith the patent statutes, we desire that our invention be interpreted asbroadly as possible and that it be not limited to the particularembodiments disclosed herein, inasmuch as it will be obvious,particularly to persons skilled in the art that many changes andmodifications may be made in these particular structures withoutdeparting from the broad spirit and scope of our invention. Therefore,we desire that the claims be interpreted as broadly as possible and thatthey be limited only by what is expressly stated therein.

We claim as our invention:

1. In a device of the character described, an insulating base memberincluding at least one projecting contact supporting portion havingangularly related contact supporting outer surfaces located in adjoiningangularly related planes, relatively stiff elongated conducting contactmeans having angularly related sections in a plane substantiallyparallel to said base and at substantially right angles to saidsupporting projection and in intimate engagement with said contactsupporting surfaces, means preventing lateral displacement of saidconducting contact means outwardly with respect to said base member, andmovable contact means supported on said base member for movement intoand out of engagement with one of said sections of said elongatedcontact means.

2. In a device of the character described, an insulating base memberincluding at least one laterally projecting contact supporting portionhaving angularly related contact supporting surfaces, elongatedconducting contact means having angularly related sections in intimatefunctional engagement with said contact supporting surfaces, rib meansintegral with said contact supporting portion for preventing lateraloutward displacement of said conducting contact means with respect tosaid base member, and movable contact means supported on said basemember for movement into and out of engagement with one of said sectionsof said elongated contact means.

3. In a device of the character described, an insulating base memberincluding at least one outwardly projecting contact supporting portionhaving angularly related adjoining contact supporting surfaces includingopposed substantially parallel surfaces and connecting surface at oneend thereof, relatively stiff elongated conducting contact means havingangularly related sections in intimate engagement with said contactsupporting surfaces, a terminal screw threadedly engaging through saidcontact means, a recess in one of said opposed surfaces for freelyreceiving said screw, and movable contact means supported on said basemember for movement into and out of engagement with one of said sectionsof said elongated contact means.

4. In a push button switch including a support member capable of beingmounted on a base in a plurality of angularly related positions andcarrying fixed and movable contact means, a button member bearingsuitable indicia on its outer end slidably mounted on said supportmember for actuating said movable contact means, releasable meanslimiting said slidable movement for permitting said member when releasedto be mounted on said support member in a difierent angular positioncorresponding to said angular positions of said support member, meansalso permitting connection of said button to said movable contact meansin different relative angular positions, whereby said indicia may bepresented in the same position for different angular mountings of saidswitch, and cooperating means on said members for preventing rotation ofsaid button at said difierent angular positions.

5. In a push button switch including a support member carrying fixed andmovable contact means, a button member bearing suitable indicia on itsouter end slidabiy mounted on said support member and pivotallyconnected to said movable contact means ioractuatin'g said movablecontact means in a plurality of relatively diflerentangular positions oisaid button, said members being 01' a molded insulation material andhaving integral therewith complementary means ior preventing rotation ofsaid button member while permitting slidable mounting of said buttonmember on said basemember in a plurality of diflerent angular positions01' said button member with respect to said base member. ,1

6. In a circuit interrupter, an interrupter casing having interruptingmeans therein and actuating means for the interrupter projecting throughan opening in a wall of said casing, said actuating means being slidablymovable through said opening, and locking means on the outer side ofsaid casing wall for movement into and out of the path of movement 01said actuating means for engagement over the outer end of said actuatingmeans for locking said actuating means in a depressed position.

7. In a circuit interrupter, an interrupter casing having interruptingmeans therein and actuating means for the interrupter projecting throughan opening in a wall of said casing, said actuating means-being. mountedfor limited sliding movement through said casing opening, and lockingmeans mounted on the outer side of said casing wall for movement in aplane disposed at an angle to the sliding movement 01' said actuatingmeans, for movement into, engages ment over the outer end oi saidactuating means when pressed to prevent outward movement thereof.

8. In a circuit interrupter, an interrupter cas-' ing havinginterrupting means therein and actuating means for the interrupterprojecting through an opening in a wall 01 said casing, said actuatingmeans being mounted for limited sliding movement through said casingopening, and locking means moimted on the outer side of said casing forpivotal and sliding movement in a plane disposed at an angle to thesliding movement or said actuating means ior movement into engagementtherewith to lock said actuating means against movement, and wherebysaid locking means may move outwardly away from said actuating means toa projecting position I with respect to said casing-and then-pivotaiiyto a position along one side of said casing.

9. In a device the character described, an insulating base memberincluding at least one projecting contact supporting portion havingangularly related contact supporting outer surfaces located in adjoiningangularly related planes, relatively stii! elongated conducting contactmeans having angularly related sections in intimate engagement with saidcontact support s suriaces, respectively, integral-rib means on saidcontact supporting portion for preventing lateral away from at least oneof said supporting surfaces.

10. In a circuit interrupter, a supporting block of insulating materialhaving a recess in one side thereof, an aperture extending through saidblock and opening at one end into said recess, said one end of saidaperture being enlarged for receiving resilient means, spaced meansintegral with said block and extending into said recess at one side ofsaid aperture to form guides substantially aligned with said aperture,arcuate I guide means at the opposite side of said aperture,

sidewise movement or said contact means outwardly relative to saidsupportingportion base membenandmeansintegralwithsaidbasemermberandoveclyingsaidcontactmeansiorprevsntingmovementorsaidcontactmcanslatsraily and contact means mountedon said block and' including spaced contact portions in said recess Pabout said aperture.

11. In a device of the type described, a support, a block oi insulatingmaterial adapted to be mounted on and secured to said support, integralprojecting contact supporting means on at least one side of said block,separate contact strip means bent about opposite ends 01' said contactsupporting means and each including a portion positioned at the outerside of said contact supporting means having means for securing aconductor thereto, and each of said strips having another partpositioned at the opposite side of said contact supporting means inspaced overlapping relation, and cooperating contact means mounted onsaid block for movement between said other spaced parts of said contactstrip means.

12. In a device of the type described, a support, a block of insulatingmaterial having a pair of spaced supporting leg portions adapted to bemounted on and secured to said support, integral projecting contactsupporting means on at least one side of said block, contact strip meansbent about said contact supporting means and including a portionpositioned at the outer. side or said contact supporting means havingmeans for securing a conductor thereto, and another portion extendinginto the space between said leg portions, cooperating contact means alsoin the space between said leg portions, and actuating means extendingthrough said block for moving said cooperating contact means into andout of engagement with said other portion of said contact strip means.

13. In a device of the type described, a support, a block of insulatingmaterial having a pair of spaced supporting leg portions adapted to bemounted on and secured to said support, integral projecting contactsupporting means on at least one side 01' said block, separate contactstrip means bent about opposite ends of said contact supporting meansand each including a portion positioned at the outer side of saidcontact supporting means having means for securing a conductor thereto,and another portion extending into the space between said leg portionsin spaced overlapping relation, cooperating contact

